Testing the 'microbubble effect' using the Cavitron technique to measure xylem water extraction curves.

Area of Science:

• Plant physiology
• Drought adaptation
• Climate change vulnerability

Background:

• Plant resistance to xylem cavitation is a key trait for drought adaptation and understanding climate change impacts.
• Vulnerability curves are crucial for assessing cavitation resistance.
• Recent advancements have improved vulnerability curve generation but introduced potential artifacts, particularly in long-vesselled species.

Purpose of the Study:

• To evaluate the reliability of the Cavitron centrifuge technique for measuring plant cavitation resistance.
• To investigate the "microbubble effect" as a potential cause of artifacts in centrifuge-based vulnerability curves, especially in species with long vessels.

Main Methods:

• Constructed vulnerability curves using the Cavitron technique with three rotor sizes across five species with varying vessel lengths.
• Generated water extraction curves without solution injection to isolate the microbubble effect.
• Tested the microbubble effect hypothesis by analyzing cavitation nucleation in open vessels.

Main Results:

• The Cavitron technique proved robust for tracheid-bearing and short-vesselled species.
• The technique showed limitations and potential artifacts in long-vesselled species.
• Results strongly supported the microbubble effect hypothesis as the primary driver of artifacts in long-vesselled species.

Conclusions:

• The Cavitron technique is suitable for cavitation resistance studies in certain plant types but requires caution with long-vesselled species.
• The microbubble effect is a significant artifact that must be addressed in future studies using centrifuge-based methods for long-vesselled plants.
• Accurate characterization of plant drought vulnerability requires careful consideration of measurement techniques and potential artifacts.